I've setup a couple of "at" jobs to execute at specific times on CentOS 5. This morning I don't see these commands in the queue ("atq"), as expected, but I also don't see were can I check whether the daemon responsible to execute them did this on time or had any issues. Unfortunately I didn't log enough info from the scripts themselves. Any ideas?

  • To those who marked this as a duplicate - the pointed answer was about setting up logging before the command is executed. My question is about digging up logs after the fact. Apr 10 '19 at 3:54

From looking at the source of the 'at' program (from the CentOS 5.3 source repository) , it looks like it is indeed logging to syslog, but only fatal errors regarding the at daemon itself are logged (for example, if you try to run 2 at daemons at the same time).

However, process executions, resulting return code and standard error/output are not logged to syslog at all. Even when turning on debug (which requires recompilation) the log messages are not very informative (for end users) and write something like :

atd[24116]: pid 24121 exited with status 0.

Which will not help you a lot in identifying which command was ran, by which user or what was its standard output/error.

atd does send an email notification to the user who requested the command, in case the command had failed, or produced anything in it's standard output/error. But for commands that succeed without any output , no mail is sent. You can change that using the -m flag.

From at(1):

-m Send mail to the user when the job has completed even if there was no output.

Borrowed from Tom Feiner's answer from almost an identical question.

  • At typically logs to syslog on all *nix systems I've encountered. The facility may vary: there isn't a dedicated one. I've seen daemon and cron used
    – voretaq7
    Aug 18 '11 at 3:31
  • Thanks for both of you for your answers. You confirmed what I suspected - if my commands don't have extra-logging then at's own logging isn't going to help. However - grep'ing for "atd" through the compressed "/var/log/messages*.gz" I found hints for the execution happening by form of PAM logs at the expected times. Although this isn't conclusive at least something happened when it was expected. Aug 19 '11 at 5:00

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